Trace Element Contents of Carbonates from Holes 549 and 550B (Leg 80): Comparison with Some Tethyan and Atlantic Sites

Abstract

The evolution through time of trace element contents (Sr, Mg, Mn, and Fe) of sediments at Sites 549 and 550 is similar to that of previously studied oceanic sites. A comparison with some North Atlantic sites and with outcrops of the Gubbio section (Italy) allowed us to show that 1. A negative correlation between Sr and Mg contents, generally characteristic of pelagic carbonate having undergone diagenesis, is confirmed.2. Magnesium diagenesis occurs over a relatively short time and is sensitive to the sedimentation rate of each individual time period, whereas Sr diagenesis is a long-term phenomenon and is sensitive to the overall average sedimentation rate at the site. Strontium loss by sediments is related to sediment age (i.e., residence time of sediments in a given diagenetic environment) and could be a rough method of dating individual sediment layers.3. The nature of the seafloor (oceanic or continental) does not appear to play an important part in the content of Fe and Mn in sediments. Their distribution depends more on mid-oceanic ridge activity, paleodepth (through mediation of CaCO 3 dissolution and environment), and distance of the site from the ridge.

New insights into geochemical behaviour in ancient marine carbonates (Upper Jurassic Ammonitico Rosso): Novel proxies for interpreting sea‐level dynamics and palaeoceanography

“…The mean value obtained (1200 p.p.m.) also falls within the lower range of Fe values reported from Fe–Mn nodules related to hydrothermal activity in the Mid‐Atlantic ridge (Andrianiazy & Renard, ).…”